We are not sure what is causing the issue but it may be related to the database file format that PD uses. It is the same file format as Microsoft Access Database Manager, .mdb.
Close Palm Desktop if not using it. Close it out before shutting down your PC. I would suggest you "clean" uninstall 6.2 and install PD version 4.1.4e. Search the forums for the "clean" uninstall instructions I have posted before. It should work on Win7 64 bit systems and does not lose data like 6.2. You can find the Win7 64 bit USB drivers at the following post, http://forums.hpwebos.com/t5/Windows-HotSync/64-Bit-Palm-Desktop-Drivers-are-HERE/m-p/337516
You can recover the data from your user folder provided you have only sync'ed once with the PC when you discovered the data missing. When you sync to the PC there are files created for each PIM category in your user folder. For Example; datebook.dat or datebook (Depending on the version of Palm Desktop) and datebook.bak. Using 6.2 the file names are .mdb and mdb.bak. For 6.2, the files are located in the username folder in PalmOSdesktop in my documents.
The files are named .dat and .bak. When you sync, the current data is stored in .dat. The next time you sync the data in the .dat file is copied to the .bak file. You can rename the .dat to .old. then rename the .bak to .dat. If the data in the .bak file is intact, it will now be in palm desktop when you reopen Palm desktop. I have included a link to show you how to find the userfolder on the PC.
http://kb.hpwebos.com/wps/portal/kb2/common/article/26674_en.html
Here is another link regarding data loss;
http://kb.hpwebos.com/wps/portal/kb2/common/article/39503_en.html
The best way to backup your data is to use the export feature in Palm Desktop. Make a new folder on the PC desktop named Palm Desktop Backup data. Next, select the category you want to export. You will get a window that asks where you want to save the file, save in the folder created on the desktop. There is a button that allows you to select currently selected record or all, select all. If you don't select all, then only the record highlighted is exported. You will then need to name the file for export, I suggest the name of the category, eg: datebook (With current date). Do this for all critical data in each category. With the data exported to the folder on the PC desktop, you can save this data to a flash drive, external hard drive or a CD-RW. With this method you will have your data in a seperate place than Palm desktop and the device. If you "Lose" data again, you can import the data back into palm desktop.
Make sure that when you make changes in palm desktop or the device to export the data to the folder created for the backup.
Here is a link for other options for backing up your data;
http://kb.hpwebos.com/wps/portal/kb2/common/article/28751_en.html
Another option is to use the program called NV backup. It is a program that you install on your device and backup to an SD card in your device. If the HH fails or you lose data, you can restore all your data from the backup.
You should always have your important data in 3 different places, on your device, the PC and another location outside of both of those. The export option is what I use because you can import the data into any version of PD.
For reference purposes, click on the following link for the support page for your device on the kb.hpwebos.com webpage.
http://kb.hpwebos.com/wps/portal/kb/na/tungsten/tx/unlocked/home/page_en.html
There are links on the page to the user guide, troubleshooting, how to's, downloads, etc.
